Optically active amino acids are important compounds used, for example, as intermediates of various pharmaceuticals. Especially, since unnatural amino acids which are highly valued as optically active intermediates are not metabolites producible by microorganisms, they cannot be produced by the production method of natural amino acids, such as fermentation. Although methods using metal catalysts are developed, they are uneconomical because transition metals are very expensive. Accordingly, an enzyme-based method may be economical and effective for production of optically active amino acids.
In this regard, α-transaminase is an industrially useful enzyme for production of optically active amino acids owing to fairly broad substrate specificity and high optical selectivity. However, its industrial utilization is limited because of low conversion rate due to small equilibrium constant.
Accordingly, for production of optically active amino acids using the enzyme-based method in industrial scale, it is necessary to overcome the low equilibrium constant of α-transaminase.
As existing methods for producing optically active amino acids using enzymes, Korean Patent Publication No. 10-2011-0047789 discloses a method for preparing an amino acid using microorganism-derived chain type transaminase and Korean Patent Publication No. 10-2008-0016287 discloses a method for producing an amino acid using β-transaminase.